Surface heat exchange apparatus for fluids



Feb. 19, 1935. R. sELlGMAN SURFACEl HEAT EXCHANGE APPARATUS FOR FLUIDSFiled Sept. l2, 1933 4 Sheets-Sheet l MVE/VTR l ATToR/vD/S l'feb. 1'9,:1935. R. sELlGMAN SURFACE HEAT EXCHANGE APPARATUS FOR FLUIDS Filedsept. 12, i955 4 sheets-sheet 2 I lllllrl/l/l lll/1111 ,arras/VEZ,

Feb. 19, 1935. R. sELlGMAN SURFACE'HEAT EXCHANGE APPARATUS FOR FLUIDSFiled Sept. 12, 1933" 4 Sheets-Sheet 3 lll/111171) /NvENT0R WSW B y mmmATTORNE x5 Feb. 19, 1935. R SELIGMAN 1,992,097

SURFACE HEAT EXCHANGE APPARATUS FOR FLUIDS Filed Sept. l2, 1953 4Sheets-Sheet 4 Wigs/[NMR mmm Patented Feb. 19,. 1935 UNITED STATESSURFACE HEAT EXCHANGE APPARATUS FOR FLUIDS Richard Seligman, Wimbledon,London, England Application september 12, 1933. serial No. 689,149 InGreat Britain April 4, 1933 6 Claims.

'I'he present invention concerns improvements in or relating to surfaceheat exchange apparatus for iiuids, of the type in which the uidsbetween which heat exchange is to be eiected ilow on opposite sides of aconductive heat exchanging surface of .extended area.

In the design of heat exchange apparatus hitherto known it has been the`practice to try to obtain the maximum possible speed of the fluids overthe heat exchanging surface with the object of promoting a high rate ofheat exchange. Such apparatus has the disadvantage that a considerableconsumption of power is required to maintain the speed of the iiuids. Asa further means of enhancing the rate of heat exchange baiiles or otherobstacles have been arranged in the path of the fluids, or the fluidshave been caused to reverse their direction of flow at frequentintervals, all of which devices cause an increase in the amount of powerconsumed in operating the heat exchanger.

'Ihe object of the present invention is, therefore, to provide a heatexchange apparatus in which the above disadvantages are largelyobviated, and in which the power consumption in relation to knownsystems is comparatively small. Such an apparatus is obviously ofconsiderable technical and industrial importance, and the invention maybe said to provide heat exchange apparatus for fluids in which it ispossible to obtain a high rate of heat exchange between the re spectivehot and cold uids with a very small drop in the pressure of the uids inpassing over the heat exchanging surfaces. In other words, the presentinvention permits a very high rate of heat exchange to be achieved atcomparatively low linear rates of fluid flow, and in consequence thedrop of pressure in the fluid between the inlet 'and outlet to theapparatus is small which as stated above is a very advantageous result.

According to the present invention heat exchange apparatus for uids, ofthe type in which the fluids between which heat exchange is to beeffected flow on opposite sides of a heat exchanging surface, ischaracterized by the features that the said heat exchanging surface isso shaped that there are formed with one or both adjacent heatexchanging surfaces or with one or both end walls of the apparatus, aplurality of restricted passages interconnecting a series of chambers,which passages are of such shape as to impart a dened directional flowto the fluid jet issuing therefrom, for example, against one or moreheat exchanging walls of the succeeding chamber.

Another feature rof the present invention comprises heat exchangeapparatus for fluids, of the type in which the fluids between which heatexchange is to be eifected ow on opposite sides of a heat exchangingsurface, characterized by 5 the feature that the said heat exchangingsurface is so shaped that there are formed with one or both adjacentheat exchanging surfaces or with one or both end walls of the apparatusa plurality of restricted passages interconnecting a l0 series ofchambers, the said passages having such shape and .dimensions inrelation to the chambers that their profileY is substantially that of aVenturi-tube, whereby 'loss of fluid pressure in passing from chamber tochamber is reduced to a Further limportant features of the presentinvention will be apparent from the following description and theappended claims.

The present invention, together with the preferred modes of carrying itinto effect, will now be described with reference to the accompanyingdrawings. These are directed to describing a form of apparatus which maybe readily taken apart for cleaning, which is essential when dealingwith some liquids, e. g., milk or beer. It will be clear, however, tothose skilled in the art that the principles involved can be readilyapplied to constructions in which such provision is not necessary as,for instance, for steam condensers and the like.

1n the drawings:-

Fig. 1 shows a sectional view on the line 1-1 of Fig. 2 of a framememberfor a heat exchanger according to the present invention; the framebeing in elevation and the packing in section.

Fig. 2 is a cross section of Fig. 1 on the line 2 2.

Fig. 3 is a plate for use in conjunction with the frame of Fig. 1 ashereinafter described. 40

Fig. 4 is a central vertical section of Fig. 3.

Fig. 5 shows one end of the plates and frames assembled in position in aheat exchanger and Fig. 5a shows the other end. 45

Fig. 6 shows an enlarged section of one of the chambersv and the inletand outlet passages thereto.

Fig. 7 shows a cross section of the plate of Fig. 3 on the line '7A-7 ofFig. 3, the frame being 50 shown between two plates.

Fig. 8 shows a modified form of frame and plate.

Fig. 9 shows a further alternative arrangement of frames and plates. 66

` 1o. snowsps -modmcstioamfwnicni the frameand plate are combined.

. t @P10-m mt 11 shows an v plates. ,Y f

Figs. 12 and 13 show cross sections of alterna- .tive'forms of platesaccording'to the presentin.

- vention.

,Corresponding elements are indicated by the same reference number inthe drawings.

'I'he frame 1,-shown in Fig. vl., consists of open rigid frame oftheshapel shown, containing on both sides channels for the reception ofresilient packing material, such as rubber rings 2.

4 Inlet and outlet ports3-and 4 respectively are provided in each frame-forone fluid, together with transfer ports 5 and'6 respectively for thesecond amd.` Adjacent the inlet and 'outlet ports supporting grids 7 areprovided to prevent the pressure of the fluid from deforming thethinplates 8 and thus causing leakage of the fluids. Lugs '9 areprovided whereby a number of frames and plates may be carried and/orclamped together by bolts, for example, in asingle unit.

'I'he plate 8 of Fig. 3 comprisesa thin metal plate for example, ofcopper, tinned copper, stainless steel etc., accordingto the nature .andproperties of the fluid .or liquids to be treated. It

- has the same overall shape as the frame 1 and contains four ports 10,1.15,- 12, 13. Ports 10 and 11 register with the inlet and outlet ports3 and 4. of the frame 1. and ports 12 and 13 register withv y r thetransfer ports 5 and 6. Ifdesired one or more of the ports 10,l 11, 12,.13 may be leftuncut according to the, direction of flow which' it isintended the fluids s'houldtake. Indentations 14,

` or troughs as they will be hereinafter called, are

formed in the plate, conveniently by preing, castingy or machining, sothat the plate has the cross section shown in Fig. 4. The shape of atrough is shown on an enlarged scale in Fig. 6.

'Ihe frames and plates are assembled alternately as shown in thelongitudinal section of Fig. 5, a suiiicient number being provided todeal lwith the quantities of liquid to be treated. It will be seen thatwhen so assembled there are formed a plurality of chambers 15,interconnected by constricted passages 16 forming throat between eachtwo chambers. One fluid or liquid (e. g. hot water) passes through oneset. of chambers and passages in series as indicated by the arrows H. W.(Fig. 5) and the other yfluid or liquid (e. g. milk) passes through thechambers and passages on theother side of the heat exchange surfaceformed` by the plate 8 preferably in contraow as indicatedby the arrowsM, heat exchange taking place between the 'two uds or liquids which arekept entirely separate by the rubber sealing devices 2, any smallleakage round the ports escaping through the channel 2a, formed betweenthe ports and the sealing means round the body of the frame. l

In order that the invention may be applied to the elements adjacent theend pieces or walls of the apparatus, between which `.end walls theplates and -frames are normally positioned, one

-. :mausi4 Y l 8. In this case the end walls of thev apparatus cooperatedirectly with the single plate. and are Vformed with troughs orprojections in their lsurfaces as'above described. If, however, inanycase it'is desired to submit only one of the fluids to the `passage.through the constrictions and chambers then, ini this case, the plate orend wall on the i opposite side of.A the heat exchanging plate may` beplane.

Referring to Figs. s and e it is seen um the profile-,or cross sectionof the passage or ,throa 16 resembles that of a Venturi-tube in that thepassage gradually narrows to a minimum cross' ing therethrough isaminimum, and it is believed that `forming the passages in this shape isan important contributory cause of the small loss of pressure in fluidsilowing throughA the apparatus of the present invention.-

Itis not necessary, according to the present invention, that the profileofthe passage 16 should be exactly that oi' a venturi; it is quitesumcient that the shape of the passageshould approximate thereto and Ihave found that very good results can be obtained if the profile of thepassage apchamber 15: the wall 14a is in contact with the other fluid inthe corresponding chamber and the result of the jetlof'uidissuing withconsiderable velocity from the aperture 16 andimpinging directlyon thesurface 14a is to effect a high degree of heat exchange through thecham' ber wall 14a with the other fluid on the opposite side of thewall. I have performed experiments to show the flow-lines of the fluidthrough the passages 16 and through the chamber 15 and I have found thatit is possible with'the arrangements of the present invention, if theproportions are suitably chosen to direct the jet of fluid against thewall 14a, and thence the main part of the fluid against the wall 17,whilst portions of the stream are reflected on to the wall 14, thusproviding that in each chamber and for each fluid there is at least onepoint at which'a fluid jet impinges directly on a heat. exchanging wall,and that impingement at two or more points can be. obtained whilst areasof stagnation are reduced to a minimum thus providing a very high degreeof heat exchanging eiiiciency coupled with a very low vpressure drop inthe uids passing through the apparatus, two highly desirable features inheat exchanging apparatus.

proximates'to the Venturi shape, i. e., i! -it pro- A The size and shapeof the passages 16 are controlled by the shape of the sides 17 of thetrough,

and the angle at which the fluid jet strikes the wall or walls of thechamber- 15 is also controllable by the same factors. I have found thatin order to provide a construction which shall 17 of the trough makeswith the plane o! the plate 8 should not be more than 80 nor less than60. 'I'he sides oi' the trough are preferably (but not necessarily) flatover the greater portion of their extent, as shown in Fig. 6` and mergeinto the bottom of the trough and into the plate in smooth curves whichprovide the approximate Venturishaped passage already described.

The shape of' the chamber 15 and of the passages 16 are furthercontrolled by the ratio of dimensions 8 and (see Fig. 6.) I have foundthat desirable ratios for for liquids having a viscosity approximatingto that of water are between 4 and 5.5 in order to obtain ease ofcleaning and convenient manufacturing conditions consistent with highrates of heat exchange and low pressure drop. As regards the rate kloratios between A and 1/i give satisfactory results, but my invention isnot limited to these ratios. The size of the passage 16 will naturallydepend on the character of the liquid to be treated-for example, whentreating brewers wort containing hops, or milk which under the influenceof heat deposits casein, the passage may have to be larger than wherewater is concerned to prevent choking, while viscous liquids, such ascream, may also need a comparatively wide passage. It will be, clearfrom the foregoing that by some sacrifice of rate of heat exchange thepressure required can be varied over a wide range.

Under certain circumstances it may be desirable to arrange that themajor axes of the ports 3 and 4 are inclined to the direction of thetroughs, instead of being parallel thereto as in Fig. 1. This may ensuremore uniform distribution of the fiuid over the plates, particularlywhere the width of the port is only about half the length of thetroughs, as in Figs. 1 and 8. The ports 5 and 6 and the apertures l0,11, 12 and 13 in the plate of Fig. 2 will be similarly inclined.Alternatively a tapered obstruction may be interposed between the portsand the rst trough. This may take the form of a swage on the plate or abar on the plate or on the frame.

Fig. 7 shows a cross section of the plate and frame assembly on a linetransverse to the direction of flow of the fluid. 'Ihe shape of the endsof the trough 14 is here illustrated. It is desirable that the ends 18of the trough, which are parallel to the direction of the flow of thefluids, should have substantially the same angle of inclination to theplane of the plate as the sides 17 of the trough which are transverse tothe direction of flow of the fluid, in order to minimizeleakage of theiiuid past the troughs and through the space 19 between the end of thetrough and the co-operating frame, while not making cleaning of thetroughs unduly diiiicult. The inner edge of the frame may also bebevelled so as to assume the shape of the area 19 shown in Fig. 7 andthereby minimize leakage by filling up the space which would otherwisebe open.

Fig. 8 shows a modied form oi' frame and plate, in which the fiuid takesa U shaped path over the plate. The troughs are arranged in two groupsside by side as shown and the iiuid is guided over the two groups insuccession by the projecting rib 20, which extends from the main frame 1and separates the two groups oi' troughs,

but leaving a gap 21 for the uid topass from one group to the other.Rubber packing may be provided on the rib 20 as on the frame 1. Insteadof using a projecting rib on the frame to guide the fluid the rib may bereplaced by a swagev or a raised groove formed in the plate, andoccupying the position o1' the rib. If desired the top of the groove maycontain a channel in which packing can be inserted.

Fig. 9 shows a further type of frame and plate ac cording to the presentinvention. In this case the troughs are arranged in three groups, andribs 20 extending from the frame cause the fiuid to make three passesover the plate between the inlet and outlet ports. If desired the ribs20 may be replaced by grooves on the plates as described with referenceto Fig. 8. The ports 3a, 4a, 5a, 6a.' are preferably of the same lengthin the direction of their major axes as the length of the troughs, asshown, in order to ensure uniform distribution of the fluid over theplates, and to` reduce as far as may be the loss of pressure on enteringand leaving the plate. It will be clear that any number of suchreversals of flow may be adopted.

Fig. 10 shows an alternative arrangement in which the frames 23 arewelded to or formed integral with the plates 8 as shown. This enablesthe number of rubber packings required to be reduced by one half, andmay be advantageous in certain circumstances.

Fig. 11 illustrates the application of cast plates to the presentinvention, the use of frames being eliminated. 'I'he plates 24 are castin the shape shown with projecting ribs 25 transverse to the directionof the flow of the fluid, so that when the plates are assembled chambers15 interconnected by approximately Venturi-shaped passages 16 are formedas in the case of Fig. 5. If desired, however, the disposition of theribs may vary on the two sides of the plate. For example. co-operatingribs on the two adjacent plates may be spaced so that the chambers onone side of a plate have different dimensions from those on the otherside, or the direction of the ow of, the iiuids on the two sides of theplate need not be parallel in this embodiment; for example, the

two uids may iiow at right angles one to the other, the ribs beingarranged accordingly. The plates contain inlet, outlet and transferports for the iiuids, as in the preceding embodiments.

Figs. l2 and 13 show alternative shapes for the troughs according to thepresent invention. In Fig. 12 the troughs have a saw-tooth crosssection, the angle 26 being approximately 90 or a little greater. InFig. 13 the plates areshaped to form Vena contracta passages with theadjacent plate when assembled. It will be seen that the fluid jetissuing from the passage 28, for example, is directed against the heatexchanging walls 29 of the succeeding chamber and the jet of the secondiiuid issuing from the passage 30 is also directed against the otherside of the plate 29, thus promoting good heat exchange between the twofluids, with a very low pressure loss.

A method of applying the invention to heat exchange apparatus which maybe convenient in certain circumstances is to form a heat exchang- 'ingor welding on side plates toclose the ends 18 of the troughs 14. Itseveral plates are assembled to form a heat exchanger, one plateattached across each side will serve to hold the whole series of platesin position. Alternatively, the edge of the heat exchanging Plate eitherformed as above or as in Fig. 3 may be bent up and soldered or welded tothe succeeding lplate to form a uid tight joint. In addition, in any 'ofthe Aarrangements described above, additional small indentations. orprojections may be provided on the plates,which indentations orprojections may be arranged at intervals along the sides or bottoms ofthe troughs 14. These' contact with adjoining plates and serve tomaintain the correct spacing of the plates. They prevent the platesbending under an excess of pressure on one side, which would change thedimensions of the throat 16. If applied to the construction described inthe preceding paragraph, the use of separate frames for spacing theplates may be dispensed with.

While certain preferred embodiments of the is to be understood that I donot wish theinvention to be considered as limited thereto, and that`modifications may'be made therein whilst retaining the principle andspirit of the invention spaced relation to each other that a pluralityof iluid conduits are formed through which the iluids are made to flowtransversely to the corrugations and of which each conduit comprises aplurality of heat exchangechambers being connected with each other bymeans of restricted passages and in which the chambers formed by thecorrugations have the form of wide, shallow grooves with inclinedlateral walls, and the restricted passages which connect the chamberswith each other are of nozzle-like cross-section with' their axes andthe longitudinal direction of the heat exchange chambers forming anobtuse angle.

2. In a heat exchange apparatus for uids, a plurality of spacedplate-like ow controlling and heat exchange elements assembled side byside, means for closing the spaces between adjacent elements at themargin thereof to provide heat exchange passages for uids between'eachtwo elements, each said element having a plurality of offset portionsfor providing in the assembly a, succession of heat exchange chamberswith plane parallel walls, each'said element also having portionspresenting surfaces angularly directed at angles between' 60 and 80degrees relative to said walls and connecting said offset portions, saidangular portions operating in the assembly to `restrict thecross-section of passage for fluid t'o a convergent-divergent form withthe minimum spacing between said angular portions less than one-half thespacing in the chambers, saidA chambers having a ratio of length in thedirection of flow to cross-sectional spacing between the walls which isbetween 4 to l and 5.5 to k1, and means for admitting uids to the spacesbetween the elements and withdrawing the same therefrom after passagethrough the successive chambers.

3. In heat exchange apparatus for fluids, at

`least three wall elements in juxtaposed relation for providing flowpassages for two fluids which are in heat exchanging relation throughthe wall of the central o ne of said three elements, the central one ofsaid elements having a plurality of substantially plane portions whichare wide in which the said one iluidviiows, said chambers beingsuccessively connected by restricted passages of convergent-divergentformation having walls thereof formed by said angular portions andhaving their axes'disposed at oblique angles to the said planeportionsso that the fluid is directed across each succeeding heatexchange `chamberand against at least one heat exchanging wall thereofand whereby abrupt changes in the direction of fluid flow are avoided.

4. In heat exchange apparatus for fluids, at least three wall elementsin juxtaposed relation for providing now passages for two fluids in heatexchanging relation through the central one of said three elements, thecentralone of said elementshaving a plurality of substantially planeportions which are wide in the direction o f uid flow and are connectedtogether by portions arranged at oblique anglesto said plane portionsand form therewith a succession of wide shallow grooves extendingtransversely to the direction of flow of one said fluid, said centralelement presenting its said portions for cooperation with another saidwall element to form from said grooves and the adjacent surface portionsof said other Wall element a succession of heat exchange chambersthrough which the said one iluid flows,

said chambers being successively connected by restricted passages ofconvergent-divergent formation having the walls formed by 'said angularportions and having their axes disposed at oblique angles to the saidplane portions so that the fluid is directed across each succeeding heatexchange chamber and against at least one heat exchanging wall thereofand whereby abrupt changes in the direction of fluid flow are avoided,the length of each said chamber being at least twice the separation ofthe parallel portion thereof from the adjacent surface portion oi' theother wall element.

-5. In heat exchange apparatus for uids, at least three. wall elementsin juxtaposed relation for providing flow passages for two fluids inheat exchanging relation through the central one of said three elements,the central one of said elements having a plurality of substantiallyplane portions which are wide in the direction of fluid ilow and areconnected together by portions arranged at angles to said plane`portions and form therewith a succession of wide shallow groovesextending transversely to the direction of now of one said iluid, saidcentral element presenting its said portions for cooperation withanother said wall element to formfrom said grooves and the adjacentsurface of said other wall element a succession of heat exchangechambers through which the corresponding fluid ilows, said chambersbeing successively connected by restricted passages ofconvergent-divergent formation having the walls formed by said angularportions and having their axes disposed at oblique angles to the saidplane portions so that the uid is directed across the succeeding heatexchange chamberand against at least one heat exchanging wall thereofand whereby abrupt changes in the direction of fluid flow are avoided,the length of each said chamber being between 4 and 5.5 times theseparation of the parallel portion from the adjacent surface of theother wall element.

6. In heat exchange apparatus for-fluids, a series of elements eachformed with a series of parallel trough-shaped depressions, the saidelements being arranged side'by side in spaced relationship so that thespace formed between each pair of juxtaposed elements comprises aplurality of heat exchange chambers which have a length in the directionof fluid now at least twice that of the distance between the elements atthe corresponding chamber and which chambers are interconnected byrestricted passages of convergentdivergent formation, the passages beingformed and arranged to cause the issuing uid therefrom vto be directedtransversely across the succeeding

